An object with a mass of 12 kg12kg is on a surface with a kinetic friction coefficient of 1 1. How much force is necessary to accelerate the object horizontally at 14 m/s^214ms2?
1 Answer
Explanation:
For this problem it is important to note that there are two forces acting on the object in the
Start by listing out the given and required values.
m=12kgcolor(white)(i)color(teal),color(white)(i)mu_k=1color(white)(i)color(teal),color(white)(i)a=14m/s^2color(white)(i)color(teal),color(white)(i)F_"app"=?m=12kgi,iμk=1i,ia=14ms2i,iFapp=?
A free-body diagram can represent the situation as:

In this case, set the positive directions to be forward and down.
Using
F_("net",y)=ma_yFnet,y=may
F_N+Fg=ma_yFN+Fg=may
Since the object does not accelerate vertically, the acceleration in the
F_N+Fg=m(0m/s^2)FN+Fg=m(0ms2)
F_N+Fg=0NFN+Fg=0N
F_N=-FgFN=−Fg
color(blue)(|bar(ul(color(white)(a/a)color(black)(F_N=-mg)color(white)(a/a)|)))
After adding the forces in the
F_("net",x)=ma_x
F_"app"+F_(f,k)=ma_x
F_"app"=ma_x-F_(f,k)
F_"app"=ma_x-mu_kF_N
F_"app"=ma_x-mu_k(color(blue)(-mg))
F_"app"=ma_x+mu_kmg
Substitute your known values.
F_"app"=(12kg)(14m/s^2)+(1)(12kg)(9.81m/s^2)
F_"app"=285.72N
F_"app"~~color(green)(|bar(ul(color(white)(a/a)290Ncolor(white)(a/a)|)))